Ultra short wave system



April 1942- c. H. BROWN 2,280,026

ULTRA SHORT WAVE SYSTEM Filed Sept. 1, 1939 2 Sheets-Sheet l M -i l I I llllF-{In- INV EN TOR. CHARLES H. BROWN ATTORNEY.

FREQUENCIES ONE OR MORE CARRIER April 14, 1942.-

C. H. BROWN ULTRA SHORT WAVE SYSTEM Filed Sept 1, 1939 2 Sheets-Sheet 2 roLoAo 27 34 GIVAL INVENTOR. CHARL H. BROWN BY '7 A TTORNEY.

Patented Apr. 14, 1942 ULTRA SHORT WAVE SYSTEM Charles H. Brown, Baldwin, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application September 1, 1939, Serial No. 293,044

11 Claims.

This invention relates to electron discharge devices and circuits therefor, for use particularly with ultra short waves below five meters.

One of the objects of the present invention is to provide an improved electron discharge device arrangement in which the electron transittime effects are minimized and which will function with relatively small losses at extremely high frequencies on the order of five meters to five centimeters,

Another object is to provide an improved electron discharge device circuit for obtaining a plurality of outputs of unrelated and/or related frequencies from a single electron beam.

A further object is to provide an electron discharge device and circuit therefor wherein a single electron beam is modulated by different carriers and there is obtained therefrom several outputs of different unrelated frequencies.

A still further object is to provide an electron discharge device arrangement including a pair of resonant tank circuits which are excited in succession by a single electron beam.

Other objects and various features of novelty will appear hereinafter from a reading of the following description.

Generally stated, the present invention consists of improvements in the ultra high frequency electron discharge device art, reference being made to the article by Dr. A. V. Haeif, entitled An Ultra High Frequency Power Amplifier of Novel Design, which appeared in Electronics for February, 1939, page 30 et seq., published by McGraw-Hill, Inc., for an understanding of the fundamental principles involved herein. The invention is useful in its application to oscillation generators, amplifiers, frequency converters and detectors, although not limited thereto.

A description of the invention follows in conjunction with drawings, given by way of example only, wherein:

Fig. 1 is a simplified diagrammatic representation of the structure of an electron discharge device employing a single electron beam for exciting a plurality of tank circuits from which outputs may be individually taken;

Fig. 2 is a longitudinal section of two tank circuits arranged according to the invention, whereby a single electron beam traverses substantially the entire length of both tanks in succession;

Fig. 3 is a modification of the circuit employing the device of Fig. 2; and

Fig. 4 shows the two tank circuits of Figs. 2

and 3 compactly arranged in a preferred mechanical construction.

Referring to Fig. 1, there is shown an electrically quarter-wave concentric live tank circuit having an outer conductor l and an inner hollow conductor 2, both of which may be cylindrical in cross-section, electrically coupled together by the conducting end plate 3. The conductors l and 2 are separated at one end by a gap 4, there being provided a second tubular conductor 5 which is an aperture extension, so to speak, of the inner conductor 2 and coaxial therewith. This tubular extension 5 and the outer conductor l are connected by conducting plate 8. This arrangement provides a quarter wave tank.

A suitable cathode I produces a beam of electrons whose density is modulated by a high frequency wave impressed by source 8 on grid 9 and which traverses the gap 4 before impinging upon the positively charged collector electrode I0. It is preferred that collector electrode Ill be a hollow structure, conical, semi-circular, rectangular or otherwise, upon whose interior the electrons impinge. By means of magnetic focusing coil H and electrostatic focusing electrode l2 the electron stream is prevented from impinging on the conductors 2 and 5. Suitable electrodes l3 maintained at a positive potential relative to the cathode serve to accelerate the electrons. T-hese electrodes as well as the cathode 1, grid 9 and electron collector I0 are positioned within an evacuated glass envelope M. The electron beam is broken up into a series of groups of electrons by the grid, and delivers high frequency power to the resonant concentric line tank I, 2, in the manner described in more detail in the article by Dr. A. V. Haeif, supra. Power may therefore be abstracted from this tank I, .2 in any suitable manner.

In order to derive separate outputs from the electron discharge device there are provided a plurality of concentric line tank circuits i5, l6, l1, l8 spaced along the length of the tank I, 2 in the manner shown. The inner conductors of these additional tank circuits are each provided with a ring 19 surrounding the electron beam for inducing a charge in the tank circuit associated with the ring as the electrons pass through the ring. The rings l9 are suitably dimensioned to provide a proper time relation between the entry of an electron into the ring and its exit from the ring, it being preferred that the time of an electron to pass through any one ring correspond to one-half a period of th wave to which the particular tank associated with that ring is tuned. Each of the tanks l5, l6, l1 and [8 are provided with separate output circuits 20, 2|, 22 and 23, respectively, comprising loops inductively coupled to the inner conductors of the tanks. It will thus be seen that if the electron beam from cathode I is modulated with different carriers, indicated herein diagrammatically by source 8 and grid 9, or putting it another way, if the electron beam is modulated by the pick-ups from different short wave stations (television or otherwise) and the tank circuits l5, l6, l1 and I8 suitably dimensioned or tuned to the frequencies of the carriers or intermediate frequencies derived therefrom, then different outputs can be taken from the loops 20, 2|, 22 and 23 to feed different receiving circuits. It is preferred, of course, that a local oscillator be employed in a separate circuit to provide the different intermediate frequencies to be impressed on grid 9, although the invention is not limited to such an arrangement. Where desired, the tanks l5, 16, I1, l8 may be dimensioned to tune to different related frequencies (i. e., multiple harmonic frequencies) or even to the same frequency. In the latter instance there will be derived output currents from tanks l5, l6, l1, l8 of the same frequency but of different phase, which, if desired, can be combined in known manner toprovide an amplified signal. will be apparent that the system of Fig. 1 provides a plurality of outputs obtainable from a single electron beam.

A suitable radio frequency input circuit I02 for varying the potential of ring l3 illustrates one way by which the electron stream may be velocit modulated between the rings l9, IQ of the auxiliary tank circuits, if so desired.

Fig. 2 illustrates an amplifier arrangement wherein two quarter wave concentric line tanks I 25 and 26, each substantially similar in construction to tank I, 2 of Fig. 1, are arranged end to end in cascade, so that a single electron beam from the cathode I traverses the lengths of the inner conductors of both tanks, to excite them in succession. Tanks 25 and 28 may have the same or different dimensions. The gaps 4, 4' across the conductors of both concentric line tanks are positioned adjacent each other to reduce the transit time of the electrons exciting the two tank circuits, thereby maintaining the same electron grouping at both gaps. An electrode 19 may be positioned between the two tanks 25 and 26 and maintained at a suitable potential for focusing the beam and a single focusing coil H may also surround the two gaps 4', 4'. The electron collector electrode 10' and the various accelerating electrodes are all maintained at suitable positive potentials relative to the cathode I. Individual output circuits 21 and 28 are respectively coupled to the two tanks 25 and 26. If desired, these two outputs can be combined in a single circuit in known manner to provide an amplified output in which case both tanks will have identical dimensions.

Fig. 3 shows a modification of the system of Fig. 2, wherein the first tank 25 is employed as an oscillator stage, while the second tank 26 is employed as an amplifier or output stage. In Fig. 3 th output circuit 21 is utilized as a feedback circuit to modulate the electron stream, while the output circuit 28 extends to a suitable utilization circuit. If it is desired to modulate the oscillations produced by the oscillator stage for transmission purposes, there may be em- From what is stated above, it

ployed, by way of example, a suitable frequency modulating circuit such as vacuum tube 29 to the control grid of which is coupled a source of signals 30 and to whose screen grid and anode are coupled loops 3| and 32, respectively, electrostatically isolated from each other by a shield 33. In circuit with the loop 31 there is provided a 90 phase changer 34 so adjusted that tube 29 will draw either a leading or a lagging current, as desired, thus providing minimum amplitude modulation accompanying the desired frequency modulation. By adjusting stage 25 to be an amplifier, as by disconnecting the feed-back circuit 21 by means of switch 5| and inserting in the circuit a stable sourc of carrier oscillations 8 by means of switch 50, there will be obtained phase modulation effects.

Fig. 4 shows a preferred compact mechanical construction for the two tank circuits of Figs. 2 and 3. In Fig. 4 a single partition wall 35 separates the two tanks and further reduces the electron transit time between the gaps of the two tanks. In this construction, member 36 may be isolated for direct current potential from the rest of the tank circuits and maintain at a direct current potential suitable for additional focusing.

It should be distinctly understood that the invention is not limited to the precise arrangements shown and described, since various modifications may be made without departing from the spirit and scope thereof. For example, in Fig. 1, where different pick-ups are initially impressed upon the electron stream, the individual tanks l5 to I8, respectively, may be tuned to different intermediate frequencies, and derive energy of these frequencies from the electron stream; in this way the electron discharge device of the invention may function as a frequency converter.

What is claimed is:

1. The method of operating an electron discharge device which comprises the steps of causmg the initiation of a space flow of electrons, causing said flow to be subjected to successive processes of density and velocity modulation in accordance with certain signal intelligence, and inductively abstracting energy from said stream along different portions over the length thereof, subsequent to the velocity modulation process.

7 2. The method of operating an electron discharge device which comprises the steps of causing the initiation of a space flow of electrons, causing said flow to be subjected to successive processes of density and velocity modulation, applying a signal to vary the degree to which the density modulation process is effective, and inductively abstracting energy from the stream along different portions over the length thereof, subsequent to the velocity modulation process.

3. The method of operating an electron discharge device which comprises producing a stream of electrons along the axis of said device, modulating said stream of electrons with different carrier frequencies, and abstracting from said modulated stream along different portions of the length "thereof energy at different frequencies.

4. In a receiving system, an electron discharge device having means for producing an electron stream, means for modulating said stream with different carrier frequencies, and a plurality of differently tuned resonant circuits spaced along the length of said modulated stream and in coupling relation thereto for abstracting therefrom energy at different frequencies, different translating circuits coupled to said resonant circuits, and a collector electrode for gathering the electrons.

5. The method of operating an electron discharge device having a tank circuit in the form of a plurality of conducting coaxial tubular members separated by a gap, which comprises injecting a stream of electrons axially within the inner one of said tubular members, modulating said stream of electrons by difierent unrelated carrier frequencies, abstracting from said modulated stream along different portions of the length thereof energy at difierent frequencies, projecting said stream past said gap, and collecting the electrons after passing through said tubular members.

6. An electron discharge device having a pair of conducting members separated by a gap, a conducting member connected to said pair of conducting members to form an oscillating circuit,means for projecting a stream of electrons across said gap, means for modulating said stream of electrons with diflerent carrier frequencies prior to its passage across said gap, means for abstracting from a plurality of locations along the length of said modulated stream prior to its passage across said gap energy at difierent frequencies, and means for collecting the electrons passing through said tubular members.

7. In an ultra short wave receiving system, electron discharge. device apparatus having means for producing an electron stream, means for modulating the density of said stream in accordance with the intelligence impressed on the waves received by said system, a series of parallelly arranged concentric line resonators placed along the length of said modulated stream and in coupling relation thereto. whereby said resonators are successively excited by the passage of the electrons in said stream, and means for deriving energy from each of saidconcentric line resonators.

8. In a receiving system, an electron discharge device having means for producing an electron stream, means for modulating said stream with different carrier frequencies, and a plurality of elements spaced along the length of said modulated stream for deriving energy therefrom, and difierent translating circuits coupled to said elements.

9. Apparatus in accordance with claim 8, characterized in this that said plurality of elements constitute resonant circuits.

10. Electron discharge apparatus comprising a hollow resonator having a gap, means for projecting a stream of electrons through the interior of said resonator and across said gap including a cathode electrode and a collector electrode on opposite sides of said resonator, means for modulating the density of said stream in accordance with high frequency waves including a grid electrode located between said cathode and the gap of said resonator, and means for subsequently modulating the velocity of said stream.

11. In combination, electron discharge device apparatus having means for producing an electron stream, means for modulating said stream with a carrier frequency, means for subsequently modulating said stream with a difierent'frequency, and a plurality of tuned circuits tuned to different intermediate frequencies spaced along said stream for abstracting from said stream energy of said difierent frequencies.

CHARLES H. BROWN.

DISCLAIMER 2,280,026.07zarles H. Brown, Baldwin, N. Y. ULTRA $110111 WAVE SYSTEM. Patent dated Apr.- 14, 1942. Disclaimer filed Sept. 6, 1945, by the assignee, Radio Corporation of America. Hereb enters this disclaimer to claim 10 of said Letters Patent.

[ Gazette October 9, 1945.]

DISCLAIMER 2,280,026.-Oharles H. Brown, Baldwin, N. Y. ULTRA. Snoa r WAVE SYSTEM. Patent, dated Apr.- 14, 1942. Disclaimer filed Sept. 6, 1945, by the assignee, Radio Corporation Qf America. A Hereb enters this disclaimer to claim 10 of said Letters Patent.

o fizam Gazette October 9,19 .5.1

I DISCLAIMER 2,280,026.0harles H. Brown, Baldwin, N. Y. ULTRA SHORT WAVE SYSTEM. Patent dated April 14, 1942. Disclaimer filed December 2,- 1944, by the assignee, Radio Corporation of America.

Hereby enters this disclaimer to claims 1 and 2 of said patent} [Oflicial Gazette January 2, 1945.] 

